Modern automatic central station vacuum waste collection systems can
be of significant advantage in a nonwoven production operation. These
systems meet environmental demands for a cleaner workplace and cleaner
air. They also provide major improvements in product quality while
offering economic advantages.

The problems of handling waste fiber, dust, lint and edge trim have
had a progression of solutions according to the then available
technology. In the past, labor pools were large and inexpensive and
machinery was relatively slow. In addition, the fiber processed was
comparatively low cost and there was no great concern for fiber
reclamation, environmental quality or waste disposal.

These facts added up to a low priority for waste management and
reclamation. However, in 1989 and into the foreseeable future, waste
management is of vital concern in the entire textile processing industry
and very definitely includes nonwoven plants.

Five System Options

The ideal solution to these problems is to efficiently collect
waste wherever it is produced and convey it to a predetermined location(s) for disposal, direct reuse or reclamation. This function has
generally been performed in one of five different ways, singly or in
combination. These are manually, by fan, by mechanical methods (auger,
conveyor), by portable vacuum or by central station vacuum systems.

Each of these methods has its special role. Defective fabric rolls
and start-up strikeoffs, cardboard and large wastes can best be handled
manually by cart. If a considerable amount of air volume must be moved
to collect dusty air from a room or hood at a garnett or picker, or if
flock needs to be collected from a shear ledger blade or a napper, a
proper fan with a high air flow and relatively low air pressure is
appropriate. Mechanical conveyors move bulk for short distances.
Portable vacuum units are typically used for very small limited use
applications.

Central vacuum waste collection systems offer unique solutions.
These do not replace all other systems of waste collection, but operate
as a useful adjunct.

Modern high speed machines are often directly linked to other
machines in a production operation and a problem with one unit affects
the entire line. The more machines linked and the higher the production
line speed, the more costly the downtime. To stop a machine to manually
clean out waste is expensive. If this waste is allowed to build up, for
example, under a card or garnett, product contamination will result in
lower product quality. Automatic timely collection of waste is an
obvious advantage and automatic central station vacuum systems excel in
this function.

Mechanical waste collection by auger or conveyor is useful in some
areas but is limited to short distance transport situations.

Fans are essential in large air volume applications, but for most
waste handling requirements they are not as efficient as a centrifugal exhauster for the same amount of work.

Fans cannot convey material long distances without the use of
booster fans. Central vacuum systems can extend thousands of feet around
a mill with no diminution of vacuum pressure. Fan systems tend to be
sized for immediate requirements and not easily expanded. A properly
designed central vacuum system is capable of extensive expansion.

Hoses and floor sweep stations are easily added to existing waste
collection lines (headers) from the existing waste house. Automatic
valves are generally controlled by programmable controllers that are
easily expanded to accommodate additional automatic valves. A further
advantage of a central vacuum system is that it is easier to protect
from the risk of fire.

Automatic Central Vacuum Systems For Here And Now

An automatic central station vacuum collection system is comprised
of a waste house and the vacuum inlets. The waste house is made up of a
vacuum source, an automatically emptying waste receiver (primary
separator), a fine dust filter (secondary separator) and a waste
receptacle. The vacuum inlets are various hose stations and floor sweep
stations placed around the machinery and automatic collection nozzles
positioned throughout the plant at cleaners, openers, condensers, cards
and filter bags.

The automatic discharge vacuum receiver (primary waste receiver)
discharges collected waste into a baler, compactor or other waste
receptacle. In general, this is a timed interval but, when the receiver
is equipped with a level detector, the detector senses a full receiver
load and interrupts the timed cycle for emptying. The timed cycle
accommodates the normal automatic valve volume and the level detector
overrides this during periods of high volume collection such as work
shift change or increased manual cleaning.

"Central" refers to the location of the waste house with
all vacuum inlets leading to it. It is generally located near a shipping
dock to facilitate storage, handling and shipment of waste bales formed
automatically by the waste baler. Bales are always the same size and
weight.

A central station system can be considered by practically any
nonwoven plant or other textile manufacturing operation regardless of
size. A moderately sized typical waste house would consist of a
centrifugal exhauster with a 60-100 HP motor, a fine dust filter with
pulse jet bag cleaning and twin automatic waste receivers (to supply a
constant vacuum) automatically emptying to a waste
receptacle--compactor, baler, cart or feed bin. Automatic horizontal
balers are the most useful waste receptacles and can be supplied
according to requirement. Bales can be used for sale, disposal, storage
for later use or for reclamation blending.

A centrifugal exhauster normally provides the most economical
vacuum source. Once this type of pulp reaches its operating pressure
level, increased amperage occurs with increased air volume, so the cost
of using the system varies directly with the actual use of the system.
The waste receiver collects the waste and automatically empties it
directly to a waste receptacle for reuse or disposal. The dusty air
passes through a separator screen to a secondary receiver or dust
filter, where the dust is filtered from the air stream and manually or
automatically collected for disposal. The clean air is then returned to
the exhauster.

Automatic valves are placed on nozzles especially designed for each
application and collect waste intermittently where it is being
constantly collected by fan or free fall. When a vacuum inlet on a
central vacuum system is opened to the atmosphere (valve opens), the
result is a "vacuum implosion." This implosion draws waste
into the small diameter conveying line with great force and transports
this waste to the vacuum waste receiver with accelerated velocities
exceeding 150 feet a second. The tube couplings must be sturdy and
tightly sealed and the fittings must be designed for proper flow angles
to minimize frictional losses.

Dust Free Collection

The system itself is designed to convey waste dust-free and it is
self-cleaning in that the dust particles are separated from the dust
laden air in the secondary separator so the exhausted air can be
directed outdoors or even back into the mill. The temperature of the
exhausted air is normally about 70 [degrees] F above the ambient
temperature so some mills enjoy an economic advantage by returning
heated air back to the mill during the winter months.

Negative room pressures cause air currents to occur that disturb
dust particles and keep them in suspension. This contaminated air is
unhealthy for employees, often affects their work attitude and can
reduce product quality. Central vacuum systems operate with high
pressure (six to 12 inch Hg) and low air volume (1500 CFM to 4000 CFM).
Because only small quantities of air are removed, negative room
pressures are not created.

Many plants clean machines and work areas with compressed air "blow downs." Clean, dry compressed air is costly and can be
physically hazardous if not properly used. The judicious use of vacuum
hoses and floor sweep stations can often eliminate the use of compressed
air for cleaning purposes. This advantage of a central vacuum system can
result in lower product contamination and improved employee safety.

Employee safety is also involved with environmental quality in
other ways. Respirable air quality is the most obvious advantage of
improved environmental quality. The use of automatic valves and the
corresponding reduction in physical contact with dust avoids direct
"prolonged" contact with potentially hazardous waste such as
raw cotton dust, chemically treated fibers and bonding resins.

Automatic Filter Bags

Special filter bag sets with top and bottom valves for automatic
simultaneous emptying and cleaning of the filter bag material are
available commercially (Figure 1). When the filter bags are emptied one
at a time by vacuum implosion, closing the top valve of the bag being
emptied of waste causes a reverse air flow through the filter media and
helps to keep it clean. These filter bags are typically used to collect
lint and dust picked up by fan systems.

Filter bags let the air pass through and retain the lint, dust or
waste fiber for automatic collection by the vacuum system. They are
typically located adjacent to the machinery they serve, or at least in
the same area so negative room pressure is not produced and smaller
motors are required to power the collection fans. Because these filter
bags are self cleaning and automatically emptied, over time they do not
present increased back pressure to the fan.

The use of the automatic filter bags, therefore, contributes to
both product and environmental quality. By eliminating the need to stop
production equipment to empty these bags, downtime is reduced, output is
increased and direct manual labor to empty filter bag socks, canisters
or storage plenums is eliminated.

The Economic Advantages

Central station vacuum systems can automatically collect fiber
waste and deposit it directly to reclamation systems. The selection of
waste receiver type and of the screen separator used in the automatic
waste receiver aids in the removal of fine dust from loose fiber before
it is introduced to the reclamation equipment for further processing.

At the reclamation unit, low grade "trash" is picked up
automatically by the vacuum system and deposited in the disposal
receptacle, while the high grade reclaimed fiber is collected and
conveyed to the high grade fiber receptacle. A modern waste collection
can separately collect various grades of waste throughout a mill and
deposit these wastes according to requirements (Figure 2).

Through the use of newly developed waste receivers and fine dust
collection equipment, expensive resins used in the thermal bonding
process can be salvaged for reuse. Some uncured and partially cured
resin can be separated from the fiber waste for blending with new resin
at air lay lines. In some cases the fiber can also be recycled. An
additional advantage of this reclamation of fiber and resin is to
improve environmental quality by handling this resin/fiber mixture by
vacuum in a dust free system that will improve respirable air and avoid
skin contact by plant personnel.

By separating wastes into high and low grade products there are
many economic as well as environmental advantages. The environmental
advantages are in producing less incinerator pollution and in slowing
the rate of filling land-fills. Economically, fiber which is recycled or
reclaimed is fiber that does not need to be repurchased; in addition, it
is fiber that the mill does not have to pay to have trucked to a
landfill or incinerator.

Special Nozzles For Automatic Collection

Mills cannot always schedule their production lots advantageously,
so small and large lots may become mixed and certain colors or fibers
from one lot would reduce product quality if mixed with the next. Two
special vacuum systems that assist mills to effectively overcome this
problem for those operating cards and garnetts are in operation in many
plants today.

In the first instance, a nozzle is placed under the card or garnett
or between the card and feed bin where fiber falls out. Vacuum implosion
applied intermittently cleans the fiber from this area. Undercard cleaning is extremely effective when performed with vacuum implosion.
Fan pressures are not sufficient to draw into the nozzle the mass of
fiber that forms in this area. When the under card system is blocked,
the air follows the path of least resistance and improves top card
cleaning. When existing under card cleaning systems are replaced with
vacuum cleaning, the top card cleaning is also improved.

The second system consists of a series of small nozzles packed at
the shoulder of each worker and stripper cylinder to keep the fiber from
migrating onto the journals and into the bearing. Aside from reducing
cleanup time between lots, these nozzles also keep synthetic fiber from
melting in the bearing. Fiber collected can be directly returned to the
feed bin for re-use.

Automating Trim Collection

Handling continuous edge trim in a nonwoven production line is
usually a manual operation. The continuous trim falls into a box or onto
the floor and must be taken away at routine intervals. Some trim lines operate on the "fan" venturi principle to move the trim in a
continuous ribbon to a collection point adjacent to the machine or
nearby. Adding a chopper to cut the trim into pieces greatly increases
the density of the collecting unit and increases the time between
removing the collected trim containers.

When using a central vacuum system, the chopper can be inserted
into the vacuum line at trim lines at various plant locations and the
small cut pieces are picked up and conveyed 1000 feet or more by
constant vacuum to a waste receptacle. This eliminates completely the
manual labor to collect the trim while taking advantage of the increased
density of the chopped trim to pack more compactly in the waste
receptacle.

It is also possible with a central vacuum system to treat the edge
trim like any other intermittent automatic valve situation. The chopper
can be inserted in line with a venturi--or preferably a material
handling fan--which would deposit the pieces in a funnel or filter bag
for automatic cleaning.

Flexible Programmable Controls

In some mills there are hundreds of automatic valve waste
collection positions. To further improve the usefulness of a central
vacuum system, it is important to schedule certain valves to open at
specific intervals. The use of programmable controllers (PLC) permits
this flexibility.

Today's programmable controllers can be easily expanded or
reprogrammed to suit the mill's waste requirements. A single PLC
can control both the waste house functions as well as the mill's
automatic valve requirements. Diagnostic units can pinpoint control
problems and alert mill maintenance.

The PLC controls automatic valves. These valves are generally six
and eight inches in diameter. Due to size and speed of these valves, the
lack of need to "balance" air flows, and the use of installing
conveying lines and vacuum systems with PLC controls are capable of much
more flexibility than fan systems.

Some advantages of an automatic central station vacuum waste
collection system are:

* A measurably cleaner mill environment

* Improved product quality

* Dollar saving through reduced machine downtime, reduced labor
costs, lower health cost, lower health and fire insurance rates, low
vacuum system operating cost, the ability to economically separate high
and low grades of waste to reduce the amount of waste for disposal and
to reclaim and reuse as much fiber as possible that has already been
paid for.

There are already many useful applications of a high vacuum low
(air) volume system. As new production machinery and conditions are
developed, mills find new ways to further extend the usefulness of this
vacuum system to meet these new situations. Special nozzles,
newly-designed waste receivers, methods of handling fine dust and new
concepts involving separation of waste grades and of waste reclamation
are being developed constantly as the system is updated.

Industrial waste is more and more an area to be carefully
controlled for a variety of reasons and plant management can use
today's more sophisticated vacuum waste collection systems as an
extremely useful tool in efficient mill operation. [Figure 2 Omitted]